As electronic devices (e.g., smartphones, tablets, etc.) increasingly store and access personal/private data, the protection of such devices and data is becoming more critical. Current security measures (e.g., ID and password or PIN) provide limited protection because they are often reused and can be hacked, stolen, or forgotten. Security measures involving physiological biometrics (e.g., fingerprints, iris scans, etc.) offer increased security, but do not eliminate all security risks. For example, after initial authentication another person could fraudulently use the device if the device was lost or stolen, or if the user was coerced to authenticate.